feat: add support for custom server notifications - #580

Merged
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom
bolinfest:pr580
Dec 16, 2025
Merged

feat: add support for custom server notifications#580
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom
bolinfest:pr580

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@bolinfestbolinfest commented Dec 9, 2025•
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#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.

MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change replaces CustomClientNotification
with a more general CustomNotification type that can be used in both directions.

  • CustomNotification can carry arbitrary methods/params while
    still preserving meta/extensions; wires it into the ServerNotification union
    and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    and asserts the client sees the method and payload

Test:

cargo test -p rmcp --features client test_custom_server_notification_reaches_client

@github-actionsgithub-actionsBot added T-test Testing related changes T-config Configuration file changes T-core Core library changes T-handler Handler implementation changes T-model Model/data structure changes labels Dec 9, 2025
@bolinfest

bolinfest commented Dec 11, 2025

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@alexhancock hopefully this is relatively straightforward to review since it mirrors #556

alexhancock
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LGTM in terms of approach!

But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type

@bolinfest

bolinfest commented Dec 16, 2025

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@alexhancock ah, so with the current implementation, we have these two things:

ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);

I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!

@bolinfest
bolinfestforce-pushed the pr580 branch 2 times, most recently from 57522cf to 0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest

bolinfest commented Dec 16, 2025

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@alexhancock please re-review now that:

  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests

alexhancock
alexhancock approved these changes Dec 16, 2025
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Yeah, looks great now. Thanks!

@alexhancock
alexhancock merged commit 2e3cc4a into modelcontextprotocol:mainDec 16, 2025
11 checks passed
@github-actionsgithub-actionsBot mentioned this pull request Dec 15, 2025
Merged
bolinfest added a commit to bolinfest/rust-sdk that referenced this pull request Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest mentioned this pull request Dec 16, 2025
Merged
bolinfest added a commit to bolinfest/rust-sdk that referenced this pull request Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit to bolinfest/rust-sdk that referenced this pull request Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit to bolinfest/rust-sdk that referenced this pull request Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit to bolinfest/rust-sdk that referenced this pull request Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit to bolinfest/rust-sdk that referenced this pull request Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit that referenced this pull request Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit to earthlings-dev/rmcp that referenced this pull request Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit to earthlings-dev/rmcp that referenced this pull request Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
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@bolinfest@alexhancock
, 'i'); if (__m === '*' || __re.test(location.href)) { injectUserscript("// Add copy buttons to all 
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}
} catch(__e) { console.warn('[Userscript:Add Copy Buttons to Code Blocks]', __e); }
})();
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try {
var __m = "github.com";
var __re = new RegExp('^' + "github\\.com" + '

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feat: add support for custom server notifications - #580
Merged
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Dec 16, 2025
Merged
feat: add support for custom server notifications#580
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
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@bolinfest
@bolinfestbolinfest
commented
Dec 9, 2025•

edited

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#556 introduced support for

custom client notifications, so this PR makes the complementary change, adding

support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,

may wish to handle custom server notifications that are not part of the

standard MCP specification. This change replaces CustomClientNotification

with a more general CustomNotification type that can be used in both directions.
  • CustomNotification can carry arbitrary methods/params while
    
still preserving meta/extensions; wires it into the ServerNotification union
    
and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    
and asserts the client sees the method and payload
Test:
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-config
Configuration file changes
T-core
Core library changes
T-handler
Handler implementation changes
T-model
Model/data structure changes
labels
Dec 9, 2025
@bolinfest
bolinfest
commented
Dec 11, 2025

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@alexhancock hopefully this is relatively straightforward to review since it mirrors #556
alexhancock
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reviewed
Dec 16, 2025
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LGTM in terms of approach!
But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock ah, so with the current implementation, we have these two things:
ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);
I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!
@bolinfest
bolinfestforce-pushed
the
pr580
branch
2 times, most recently
from
57522cf to
0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock please re-review now that:
  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests
alexhancock
alexhancock
approved these changes
Dec 16, 2025
View reviewed changes
@alexhancockalexhancock
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Yeah, looks great now. Thanks!
@alexhancock
alexhancock
merged commit 2e3cc4a
into
modelcontextprotocol:mainDec 16, 2025

11 checks passed

@github-actionsgithub-actionsBot
mentioned this pull request
Dec 15, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest
mentioned this pull request
Dec 16, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit
that referenced
this pull request
Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
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@alexhancockalexhancockalexhancock approved these changes
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, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Force GitHub README to respect dark mode\n(function() {\n var style = document.createElement('style');\n style.textContent = '\n .markdown-body {\n color-scheme: dark light;\n }\n .markdown-body pre { background: #161b22 !important; }\n .markdown-body code { background: rgba(110, 118, 129, 0.4) !important; }\n .markdown-body table th, .markdown-body table td { border-color: #30363d !important; }\n .markdown-body img { background: #0d1117; }\n .markdown-body blockquote { border-left-color: #8b949e; }\n .markdown-body hr { border-color: #30363d; }\n ';\n document.head.appendChild(style);\n})();", "GitHub Dark Mode README Fix");
}
} catch(__e) { console.warn('[Userscript:GitHub Dark Mode README Fix]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
feat: add support for custom server notifications - #580
Merged
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Dec 16, 2025
Merged
feat: add support for custom server notifications#580
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
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@bolinfest
@bolinfestbolinfest
commented
Dec 9, 2025•

edited

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Contributor
#556 introduced support for

custom client notifications, so this PR makes the complementary change, adding

support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,

may wish to handle custom server notifications that are not part of the

standard MCP specification. This change replaces CustomClientNotification

with a more general CustomNotification type that can be used in both directions.
  • CustomNotification can carry arbitrary methods/params while
    
still preserving meta/extensions; wires it into the ServerNotification union
    
and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    
and asserts the client sees the method and payload
Test:
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-config
Configuration file changes
T-core
Core library changes
T-handler
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T-model
Model/data structure changes
labels
Dec 9, 2025
@bolinfest
bolinfest
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Dec 11, 2025

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@alexhancock hopefully this is relatively straightforward to review since it mirrors #556
alexhancock
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LGTM in terms of approach!
But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type
@bolinfest
bolinfest
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Dec 16, 2025

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@alexhancock ah, so with the current implementation, we have these two things:
ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);
I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!
@bolinfest
bolinfestforce-pushed
the
pr580
branch
2 times, most recently
from
57522cf to
0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock please re-review now that:
  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests
alexhancock
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approved these changes
Dec 16, 2025
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Yeah, looks great now. Thanks!
@alexhancock
alexhancock
merged commit 2e3cc4a
into
modelcontextprotocol:mainDec 16, 2025

11 checks passed

@github-actionsgithub-actionsBot
mentioned this pull request
Dec 15, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest
mentioned this pull request
Dec 16, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit
that referenced
this pull request
Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
Sign up for freeto join this conversation on GitHub.
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Reviewers

@alexhancockalexhancockalexhancock approved these changes
@jokemanfirejokemanfireAwaiting requested review from jokemanfire
@4t1454t145Awaiting requested review from 4t145

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@bolinfest@alexhancock

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Highlight search terms from Google/DuckDuckGo/Bing referrer\n(function() {\n var ref = document.referrer;\n var terms = [];\n \n if (ref.includes('google.com') || ref.includes('duckduckgo.com') || ref.includes('bing.com')) {\n var url = new URL(ref);\n var q = url.searchParams.get('q') || url.searchParams.get('p');\n if (q) {\n terms = q.split(/\\s+/).filter(function(t) { return t.length > 2; });\n }\n }\n \n if (terms.length === 0) return;\n \n var style = document.createElement('style');\n style.textContent = '.userscript-highlight { background: #fbbf24; color: #1a1a2e; padding: 1px 3px; border-radius: 2px; }';\n document.head.appendChild(style);\n \n function highlight(node) {\n if (node.nodeType === 3) { // text node\n var text = node.textContent;\n var found = false;\n terms.forEach(function(term) {\n var regex = new RegExp('(' + term.replace(/[.*+?^${}()|[\\]\\\\]/g, '\\\\') + ')', 'gi');\n if (regex.test(text)) {\n found = true;\n var frag = document.createDocumentFragment();\n var parts = text.split(regex);\n parts.forEach(function(part, i) {\n if (i % 2 === 0) {\n frag.appendChild(document.createTextNode(part));\n } else {\n var span = document.createElement('span');\n span.className = 'userscript-highlight';\n span.textContent = part;\n frag.appendChild(span);\n }\n });\n node.parentNode.replaceChild(frag, node);\n }\n });\n } else if (node.nodeType === 1 && node.childNodes) { // element\n var skipTags = ['SCRIPT', 'STYLE', 'NOSCRIPT', 'TEXTAREA', 'INPUT', 'SELECT'];\n if (!skipTags.includes(node.tagName)) {\n Array.from(node.childNodes).forEach(highlight);\n }\n }\n }\n \n highlight(document.body);\n \n // Re-highlight on dynamic content\n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1 || node.nodeType === 3) highlight(node);\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Highlight Search Terms");
}
} catch(__e) { console.warn('[Userscript:Highlight Search Terms]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
feat: add support for custom server notifications - #580
Merged
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Dec 16, 2025
Merged
feat: add support for custom server notifications#580
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Conversation
@bolinfest
@bolinfestbolinfest
commented
Dec 9, 2025•

edited

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Contributor
#556 introduced support for

custom client notifications, so this PR makes the complementary change, adding

support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,

may wish to handle custom server notifications that are not part of the

standard MCP specification. This change replaces CustomClientNotification

with a more general CustomNotification type that can be used in both directions.
  • CustomNotification can carry arbitrary methods/params while
    
still preserving meta/extensions; wires it into the ServerNotification union
    
and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    
and asserts the client sees the method and payload
Test:
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-config
Configuration file changes
T-core
Core library changes
T-handler
Handler implementation changes
T-model
Model/data structure changes
labels
Dec 9, 2025
@bolinfest
bolinfest
commented
Dec 11, 2025

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ContributorAuthor
@alexhancock hopefully this is relatively straightforward to review since it mirrors #556
alexhancock
alexhancock
reviewed
Dec 16, 2025
View reviewed changes
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•

edited

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LGTM in terms of approach!
But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock ah, so with the current implementation, we have these two things:
ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);
I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!
@bolinfest
bolinfestforce-pushed
the
pr580
branch
2 times, most recently
from
57522cf to
0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock please re-review now that:
  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests
alexhancock
alexhancock
approved these changes
Dec 16, 2025
View reviewed changes
@alexhancockalexhancock
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Yeah, looks great now. Thanks!
@alexhancock
alexhancock
merged commit 2e3cc4a
into
modelcontextprotocol:mainDec 16, 2025

11 checks passed

@github-actionsgithub-actionsBot
mentioned this pull request
Dec 15, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest
mentioned this pull request
Dec 16, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit
that referenced
this pull request
Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
Sign up for freeto join this conversation on GitHub.
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@alexhancockalexhancockalexhancock approved these changes
@jokemanfirejokemanfireAwaiting requested review from jokemanfire
@4t1454t145Awaiting requested review from 4t145

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@bolinfest@alexhancock

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Strip utm_, fbclid, gclid, etc. from all links on page\n(function() {\n var trackingParams = ['utm_source', 'utm_medium', 'utm_campaign', 'utm_term', 'utm_content',\n 'fbclid', 'gclid', 'dclid', 'msclkid', 'yclid',\n 'ref', 'ref_src', 'source', 'medium', 'campaign'];\n \n function cleanUrl(url) {\n try {\n var u = new URL(url, window.location.origin);\n var changed = false;\n trackingParams.forEach(function(p) {\n if (u.searchParams.has(p)) {\n u.searchParams.delete(p);\n changed = true;\n }\n });\n return changed ? u.toString() : url;\n } catch (e) {\n return url;\n }\n }\n \n function cleanLinks() {\n document.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n \n cleanLinks();\n \n var observer = new MutationObserver(function(mutations) {\n mutations.forEach(function(m) {\n m.addedNodes.forEach(function(node) {\n if (node.nodeType === 1) {\n if (node.tagName === 'A') cleanLinks();\n node.querySelectorAll('a[href]').forEach(function(a) {\n var clean = cleanUrl(a.href);\n if (clean !== a.href) a.href = clean;\n });\n }\n });\n });\n });\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "Remove Tracking Parameters from Links");
}
} catch(__e) { console.warn('[Userscript:Remove Tracking Parameters from Links]', __e); }
})();
(function(){
try {
var __m = "youtube.com";
var __re = new RegExp('^' + "youtube\\.com" + '

Skip to content
feat: add support for custom server notifications - #580
Merged
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Dec 16, 2025
Merged
feat: add support for custom server notifications#580
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Conversation
@bolinfest
@bolinfestbolinfest
commented
Dec 9, 2025•

edited

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Contributor
#556 introduced support for

custom client notifications, so this PR makes the complementary change, adding

support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,

may wish to handle custom server notifications that are not part of the

standard MCP specification. This change replaces CustomClientNotification

with a more general CustomNotification type that can be used in both directions.
  • CustomNotification can carry arbitrary methods/params while
    
still preserving meta/extensions; wires it into the ServerNotification union
    
and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    
and asserts the client sees the method and payload
Test:
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-config
Configuration file changes
T-core
Core library changes
T-handler
Handler implementation changes
T-model
Model/data structure changes
labels
Dec 9, 2025
@bolinfest
bolinfest
commented
Dec 11, 2025

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ContributorAuthor
@alexhancock hopefully this is relatively straightforward to review since it mirrors #556
alexhancock
alexhancock
reviewed
Dec 16, 2025
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LGTM in terms of approach!
But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock ah, so with the current implementation, we have these two things:
ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);
I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!
@bolinfest
bolinfestforce-pushed
the
pr580
branch
2 times, most recently
from
57522cf to
0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock please re-review now that:
  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests
alexhancock
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approved these changes
Dec 16, 2025
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Yeah, looks great now. Thanks!
@alexhancock
alexhancock
merged commit 2e3cc4a
into
modelcontextprotocol:mainDec 16, 2025

11 checks passed

@github-actionsgithub-actionsBot
mentioned this pull request
Dec 15, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest
mentioned this pull request
Dec 16, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit
that referenced
this pull request
Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
Sign up for freeto join this conversation on GitHub.
Already have an account?
Sign in to comment

Reviewers

@alexhancockalexhancockalexhancock approved these changes
@jokemanfirejokemanfireAwaiting requested review from jokemanfire
@4t1454t145Awaiting requested review from 4t145

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Development

Successfully merging this pull request may close these issues.

2 participants

@bolinfest@alexhancock

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Auto-enable theater mode on YouTube\n(function() {\n function tryTheater() {\n var btn = document.querySelector('button[aria-label=\"Theater mode\"], ytd-player #player button[title=\"Theater mode\"]');\n if (btn && !btn.classList.contains('activated')) {\n btn.click();\n }\n }\n \n // Try immediately\n tryTheater();\n \n // Try after navigation (SPA)\n var lastUrl = location.href;\n setInterval(function() {\n if (location.href !== lastUrl) {\n lastUrl = location.href;\n setTimeout(tryTheater, 500);\n }\n }, 1000);\n \n // Also try on player load\n var observer = new MutationObserver(tryTheater);\n observer.observe(document.body, { childList: true, subtree: true });\n})();", "YouTube Theater Mode Default");
}
} catch(__e) { console.warn('[Userscript:YouTube Theater Mode Default]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

Skip to content
feat: add support for custom server notifications - #580
Merged
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Dec 16, 2025
Merged
feat: add support for custom server notifications#580
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Conversation
@bolinfest
@bolinfestbolinfest
commented
Dec 9, 2025•

edited

Loading

Copy link


Copy Markdown

Contributor
#556 introduced support for

custom client notifications, so this PR makes the complementary change, adding

support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,

may wish to handle custom server notifications that are not part of the

standard MCP specification. This change replaces CustomClientNotification

with a more general CustomNotification type that can be used in both directions.
  • CustomNotification can carry arbitrary methods/params while
    
still preserving meta/extensions; wires it into the ServerNotification union
    
and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    
and asserts the client sees the method and payload
Test:
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
T-config
Configuration file changes
T-core
Core library changes
T-handler
Handler implementation changes
T-model
Model/data structure changes
labels
Dec 9, 2025
@bolinfest
bolinfest
commented
Dec 11, 2025

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ContributorAuthor
@alexhancock hopefully this is relatively straightforward to review since it mirrors #556
alexhancock
alexhancock
reviewed
Dec 16, 2025
View reviewed changes
@alexhancockalexhancock
left a comment
•

edited

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LGTM in terms of approach!
But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type
@bolinfest
bolinfest
commented
Dec 16, 2025

Copy link


Copy Markdown

ContributorAuthor
@alexhancock ah, so with the current implementation, we have these two things:
ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);
I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!
@bolinfest
bolinfestforce-pushed
the
pr580
branch
2 times, most recently
from
57522cf to
0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest
bolinfest
commented
Dec 16, 2025

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ContributorAuthor
@alexhancock please re-review now that:
  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests
alexhancock
alexhancock
approved these changes
Dec 16, 2025
View reviewed changes
@alexhancockalexhancock
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Yeah, looks great now. Thanks!
@alexhancock
alexhancock
merged commit 2e3cc4a
into
modelcontextprotocol:mainDec 16, 2025

11 checks passed

@github-actionsgithub-actionsBot
mentioned this pull request
Dec 15, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest
mentioned this pull request
Dec 16, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit
that referenced
this pull request
Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
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@alexhancockalexhancockalexhancock approved these changes
@jokemanfirejokemanfireAwaiting requested review from jokemanfire
@4t1454t145Awaiting requested review from 4t145

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@bolinfest@alexhancock

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Remove or un-stick sticky/fixed headers that block content\n(function() {\n function unstick() {\n document.querySelectorAll('header, nav, [role=\"banner\"], .header, .navbar, .sticky, .fixed-top, [style*=\"position: fixed\"], [style*=\"position:sticky\"]').forEach(function(el) {\n if (el.style.position === 'fixed' || el.style.position === 'sticky' || \n getComputedStyle(el).position === 'fixed' || getComputedStyle(el).position === 'sticky') {\n el.style.position = 'static';\n el.style.top = 'auto';\n el.style.zIndex = 'auto';\n }\n });\n }\n \n unstick();\n \n var observer = new MutationObserver(unstick);\n observer.observe(document.body, { childList: true, subtree: true, attributes: true, attributeFilter: ['style', 'class'] });\n})();", "Kill Sticky Headers");
}
} catch(__e) { console.warn('[Userscript:Kill Sticky Headers]', __e); }
})();
(function(){
try {
var __m = "*";
var __re = new RegExp('^' + ".*" + '

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feat: add support for custom server notifications - #580
Merged
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Dec 16, 2025
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feat: add support for custom server notifications#580
alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
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@bolinfest
@bolinfestbolinfest
commented
Dec 9, 2025•

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#556 introduced support for

custom client notifications, so this PR makes the complementary change, adding

support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,

may wish to handle custom server notifications that are not part of the

standard MCP specification. This change replaces CustomClientNotification

with a more general CustomNotification type that can be used in both directions.
  • CustomNotification can carry arbitrary methods/params while
    
still preserving meta/extensions; wires it into the ServerNotification union
    
and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    
and asserts the client sees the method and payload
Test:
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
@github-actionsgithub-actionsBot
added

T-test
Testing related changes
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Configuration file changes
T-core
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T-handler
Handler implementation changes
T-model
Model/data structure changes
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Dec 9, 2025
@bolinfest
bolinfest
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Dec 11, 2025

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@alexhancock hopefully this is relatively straightforward to review since it mirrors #556
alexhancock
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LGTM in terms of approach!
But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type
@bolinfest
bolinfest
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Dec 16, 2025

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@alexhancock ah, so with the current implementation, we have these two things:
ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);
I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!
@bolinfest
bolinfestforce-pushed
the
pr580
branch
2 times, most recently
from
57522cf to
0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest
bolinfest
commented
Dec 16, 2025

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@alexhancock please re-review now that:
  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests
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Yeah, looks great now. Thanks!
@alexhancock
alexhancock
merged commit 2e3cc4a
into
modelcontextprotocol:mainDec 16, 2025

11 checks passed

@github-actionsgithub-actionsBot
mentioned this pull request
Dec 15, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest
mentioned this pull request
Dec 16, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit
that referenced
this pull request
Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
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Reviewers

@alexhancockalexhancockalexhancock approved these changes
@jokemanfirejokemanfireAwaiting requested review from jokemanfire
@4t1454t145Awaiting requested review from 4t145

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2 participants

@bolinfest@alexhancock

, 'i');
if (__m === '*' || __re.test(location.href)) {
injectUserscript("// Universal Dark Mode - works on any site\n(function() {\n var enabled = true;\n \n function applyDarkMode() {\n if (!enabled) return;\n \n // Create style element if it doesn't exist\n var style = document.getElementById('universal-dark-mode-style');\n if (!style) {\n style = document.createElement('style');\n style.id = 'universal-dark-mode-style';\n document.head.appendChild(style);\n }\n \n // Dark mode CSS - inverts colors but preserves images/video\n style.textContent = '\n /* Invert everything except media */\n html {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #1a1a2e !important;\n }\n \n /* Restore images, videos, iframes, canvas */\n img, video, iframe, canvas, svg, picture, [style*=\"background-image\"] {\n filter: invert(1) hue-rotate(180deg) !important;\n }\n \n /* Preserve specific elements that should not be inverted */\n .no-dark-mode, .no-dark-mode *,\n [data-theme=\"light\"], [data-theme=\"light\"],\n .ace_editor, .ace_editor *,\n .CodeMirror, .CodeMirror *,\n .monaco-editor, .monaco-editor *,\n .markdown-body pre, .markdown-body pre *,\n .highlight, .highlight *,\n pre code, pre code * {\n filter: none !important;\n }\n \n /* Fix common UI elements */\n .modal, .popup, .dropdown-menu, .tooltip, .popover {\n filter: invert(1) hue-rotate(180deg) !important;\n background: #2d2d44 !important;\n border-color: #444 !important;\n }\n \n /* Scrollbars */\n ::-webkit-scrollbar { background: #1a1a2e !important; }\n ::-webkit-scrollbar-thumb { background: #444 !important; }\n ::-webkit-scrollbar-thumb:hover { background: #555 !important; }\n \n /* Selection */\n ::selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ::-moz-selection { background: #4ecdc4 !important; color: #1a1a2e !important; }\n ';\n }\n \n function removeDarkMode() {\n var style = document.getElementById('universal-dark-mode-style');\n if (style) style.remove();\n }\n \n // Toggle with Alt+Shift+D\n document.addEventListener('keydown', function(e) {\n if (e.altKey && e.shiftKey && e.key === 'D') {\n e.preventDefault();\n enabled = !enabled;\n if (enabled) {\n applyDarkMode();\n console.log('[Universal Dark Mode] Enabled');\n } else {\n removeDarkMode();\n console.log('[Universal Dark Mode] Disabled');\n }\n }\n });\n \n // Apply on load\n applyDarkMode();\n \n // Re-apply on dynamic content\n var observer = new MutationObserver(function(mutations) {\n if (enabled && !document.getElementById('universal-dark-mode-style')) {\n applyDarkMode();\n }\n });\n observer.observe(document.head, { childList: true });\n \n console.log('[Universal Dark Mode] Loaded - Press Alt+Shift+D to toggle');\n})();", "Universal Dark Mode");
}
} catch(__e) { console.warn('[Userscript:Universal Dark Mode]', __e); }
})();
})();

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feat: add support for custom server notifications - #580
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alexhancock merged 1 commit into
modelcontextprotocol:mainfrom 
bolinfest:pr580
Dec 16, 2025
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feat: add support for custom server notifications#580
alexhancock merged 1 commit into
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bolinfest:pr580
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@bolinfestbolinfest
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Dec 9, 2025•

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#556 introduced support for

custom client notifications, so this PR makes the complementary change, adding

support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,

may wish to handle custom server notifications that are not part of the

standard MCP specification. This change replaces CustomClientNotification

with a more general CustomNotification type that can be used in both directions.
  • CustomNotification can carry arbitrary methods/params while
    
still preserving meta/extensions; wires it into the ServerNotification union
    
and serde so params can be decoded with params_as
  • allows client handlers to receive custom notifications via a new
    on_custom_notification hook
  • adds integration coverage that sends a custom server notification end-to-end
    
and asserts the client sees the method and payload
Test:
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
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T-test
Testing related changes
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Model/data structure changes
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Dec 9, 2025
@bolinfest
bolinfest
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Dec 11, 2025

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@alexhancock hopefully this is relatively straightforward to review since it mirrors #556
alexhancock
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LGTM in terms of approach!
But can we unify the CustomClientNotification and CustomServerNotification types into a single CustomNotification type that can be sent either direction? Would cut down on a lot of the duplicated logic we need to implement for each type
@bolinfest
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Dec 16, 2025

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@alexhancock ah, so with the current implementation, we have these two things:
ts_union!(
export typeClientNotification =
| CancelledNotification
| ProgressNotification
| InitializedNotification
| RootsListChangedNotification
| CustomClientNotification;);
ts_union!(
export typeServerNotification =
| CancelledNotification
| ProgressNotification
| LoggingMessageNotification
| ResourceUpdatedNotification
| ResourceListChangedNotification
| ToolListChangedNotification
| PromptListChangedNotification
| CustomServerNotification;);
I didn't realize it was possible to share types across the two (like CancelledNotification): will consolidate!
@bolinfest
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0a1da26CompareDecember 16, 2025 16:40
@bolinfest
feat: add support for custom server notifications
5c11c74
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
@bolinfest
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Dec 16, 2025

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@alexhancock please re-review now that:
  • I consolidated things into one CustomNotification type
  • Updated the PR body to reflect this change
  • Tightened up some of the tests
alexhancock
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Yeah, looks great now. Thanks!
@alexhancock
alexhancock
merged commit 2e3cc4a
into
modelcontextprotocol:mainDec 16, 2025

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Dec 15, 2025
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bolinfest added a commit
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that referenced
this pull request
Dec 16, 2025
@bolinfest
# feat: add support for custom requests
b24b9e5
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduce `CustomRequest` and `CustomResult` model types, wire them into the client/server request and result unions, and allow `ClientRequest::method()` to return the dynamic method name.
- Implement serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; add default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Update JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Add tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
@bolinfestbolinfest
mentioned this pull request
Dec 16, 2025
 Merged

bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
f858999
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling, plus a focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
a4498cd
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications, so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server request and result unions, and allows `ClientRequest::method()` to return the dynamic method name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject` strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
2326775
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5e1ebb1
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
bolinfest added a commit
to bolinfest/rust-sdk
that referenced
this pull request
Dec 16, 2025
@bolinfest
feat: add support for custom requests
5fba1bc
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
alexhancock pushed a commit
that referenced
this pull request
Dec 18, 2025
@bolinfest
feat: add support for custom requests (#590)
e0faf1e
#580 and #556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom server notifications (modelcontextprotoc…
9eef655
…ol#580)
modelcontextprotocol#556 introduced support for
custom client notifications, so this PR makes the complementary change, adding
support for custom server notifications.
MCP clients, particularly ones that offer "experimental" capabilities,
may wish to handle custom server notifications that are not part of the
standard MCP specification. This change introduces a new
`CustomServerNotification` type that allows a client to process
such custom notifications.
- introduces `CustomServerNotification` to carry arbitrary methods/params while
still preserving meta/extensions; wires it into the `ServerNotification` union
and `serde` so `params` can be decoded with `params_as`
- allows client handlers to receive custom notifications via a new
`on_custom_notification` hook
- adds integration coverage that sends a custom server notification end-to-end
and asserts the client sees the method and payload
Test:
```shell
cargo test -p rmcp --features client test_custom_server_notification_reaches_client
```
takumi-earth pushed a commit
to earthlings-dev/rmcp
that referenced
this pull request
Jan 27, 2026
@bolinfest
feat: add support for custom requests (modelcontextprotocol#590)
a30c34c
modelcontextprotocol#580 and modelcontextprotocol#556 introduced support for custom notifications,
so this PR takes the next logical step and adds support for custom requests:
- Introduces `CustomRequest` and `CustomResult` model types, wires them into the client/server
request and result unions, and allows `ClientRequest::method()` to return the dynamic method
name.
- Implements serde and meta handling for `CustomRequest` so `_meta` is carried through
extensions; adds default `on_custom_request` handlers that return `METHOD_NOT_FOUND` unless
overridden.
- Updates JSON schema fixtures to include the new request/result shapes and `EmptyObject`
strictness.
- Adds tests for custom request roundtrips and end-to-end client↔server handling.
- Focused integration test in `crates/rmcp/tests/test_custom_request.rs`.
For additional testing, I used this locally to update Codex to use a custom
request instead of a custom notification so that it gets an "ack" from the MCP
server to ensure it has processed the update before sending more messages:
openai/codex#8142.
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